Non-flammable water based hot forging lubricating compositions

ABSTRACT

LUBRICANT COMPOSITION COMPRISING: (A) WATER BASE, (B) CLAY THICKENER, (C) GRAPHITE, (D) BORAX, (E) SODIUM METASILICATE, (F) NON-CLAY THICKENER, (G) POLYALKOXYLATED ALKYPHENOLS.

United States Patent ABSTRACT OF THE DISCLOSURE Lubricant compositioncomprising:

(a) water base,

(b) clay thickener,

(c) graphite,

(d) borax,

(e) sodium metasilicate,

(f) non-clay thickener,

(g) polyalkoxylated alkyphenols.

This invention concerns non-flammable water-based metal workinglubricants. More particularly, this invention relates to the abovelubricants containing alkali metal metasilicates and borax, and whichhave improved characteristics over compositions of the prior art.

BACKGROUND OF THE INVENTION The metal industry is frequently used as abellweather of industrial development and the afiiuence of a country.

.Upon first blush this seems rather anomalous since most metals haverelatively little intrinsic value until they have been worked. That is,it is only after the metal has been forged, molded or otherwise shapedinto useful forms that the value of the original, unworked metalappreciates manyfold.

Forging is a process for increasing the density, toughness and strengthof the metal by grain deformation. It can be performed while the metalis in the hot state or cold. Both processes have advantages anddisadvantages. While cold forging upgrades metallurgical properties, hotforging requires the expenditure of less energy and permits greaterdeformation. Two primary factors which are especially important in hotforging operations are the rate of production and die life. The dies arevery expensive and every precaution, including the choice of properlubricants, is taken to extend die life. The use of lubricants is tominimize metal pick-up and wear. Improper lubrication can causeundesired metal slippage and can result in defective forgings.

" However, the primary requirements of lubricants, particularly in hotforging operations, is to cool down the temperature of the workpiece anddie as well as to wet the hot metal and thereby minimize frictionaletfects caused by the workpiece sliding over the die. Furtherrequirements are to eliminate the hazards of fire and minimize airpollution. Inasmuch as the die temperatures during use can range from300 F. to about 600 F., the

use of conventional soap thickened mineral oil-based caused oraccelerated corrosion.

. In view of the problems encountered with both oilbased and water-basedlubricants, a need exists to develop a water-based lubricant which, inaddition to being nonflammable, has improved hot metal wettingcharacteristics and which minimizes or inhibits corrosion.

Therefore, it is an'object of this invention to provide Patented Apr. 2,1974 water-based hot forging lubricant concentrates which havesubstantially improved wetting properties and which minimize or inhibitcorrosion.

These objects, among many others, are achieved by the preparation of theimproved non-flammable, hot forging composition where preparation isdescribed below:

A portion of the water used in the finished hot forging concentrate,usually about one-quarter to two-thirds of the total water, is chargedto an oil-free kettle or vessel of an appropriate size fitted with theusual heating, cooling and mixing means. All of the clay thickener isstirred into the kettle containing water until the clay is evenlydispersed. At the time all of the graphite used is added to the aqueousclay dispersion until a homogenous mixture is obtained. Ordinarily apreviously and separately prepared aqueous gel comprising non-claythickeners (such as sodium carboxymethylcellulose), borax and sodiummetasilicate is added to the aqueous clay dispersion until a uniformlydispersed mixture is obtained. At this point, all of the surfactant isadded with stirring followed by the addition of the remainder of thewater which has been used as rinse of the separately prepared gelcontainer. The black gelled mixture is stirred with circulation and putthrough a sieve of the desired pore size and stored for use.

The order of above blending procedure is critical to success in thatvarying the sequence of addition of the various components produces alubricant possessing inferior stability.

(A) Clay thickeners.-The favored clay thickeners are selected from thegroup consisting of finely divided particles of the montmorillonitegroup of minerals. These are expanding lattice type minerals illustratedmost commonly by bentonite and hectorite. The major difference betweenthe former over thelatter is that bentonite contains alumina as a majorconstituent while hectorite contains magnesia as a major component. Morespecifically, bentonite is a sodium aluminum silicate, while hectoriteis a sodium magnesium-fluoro-litho-silicate. Usually the particle sizeof these clays is between 0.05 mm. and 0.01 mm. in diameter and theyhave an effective specific surface of the order of 200 to 400 squaremeters per gram.

Hectorite having a specific area of the order of 300 to 350 squaremeters per gram and whose dimensions when dispersed in solution areapproximately 1 millimicron by 700 millimicrons is the preferred claythickener.

(B) Non-clay thickeners.These optional thickeners are referred to asorganic thickeners and include alkylcelluloses, polymethylvinylether-maleic anhydride, alkali metal alkylcelluloses, and mixtures ofone or more of these organic thickeners can aso be used.

A combination of hectorite with sodium carboxymethylcellulose is thepreferred thickening system when used in the ratio of about 6 parts byweight of hectorite to about 1 part by weight of sodiumcarboxymethylcellulose. Hectorite is preferred as the clay thickenerbecause of its ability to be utilized in smaller concentrations than thebentonites to obtain the same degree of gelation and also because itexhibits a greater stability in aqueous solution.

(C) Fillers.-Finely divided graphite having an average particle size ofless than 50 microns is preferred. Preferably the particle size willhave a particle size of less than 25 microns and will have a low ashcontent (less than 2.5% by weight) when fired. A mixture of graphiteranging from about 16 to 29 parts per Weight per hundred parts by weightof the finished grease is the preferred concentration. A mixture of upto 5 parts by Weight of finely particulated calcium carbonate when usedwith 16 to 29 grease, in order to more easily calculate the relativeproportions of the components present,

parts by weight of graphite appears to improve the uniformity of thefinished grease composition.

(D) Sunfactant.--The surfactants which have proven to be the most usefulof the commercially available materials are those alkoxylatedderivatives of alkylated phenols containing an average of from 2 to 30moles of alkylene oxide in the molecule, and where the alkylating groupor groups contain from 4 to 12 carbon atoms per molecule of phenol. Thefavored surfactant is nonylphenol ethoxylated with an average of fromabout 2 to 30 ethoxylate molecules. The preferred surfactant isnonylphenol contain-. ing an average of 9.5 moles of ethoxylate in themolecule.

(D) Dilution of concentrate-The lubricants may be used as formulated orcut back by diluting with water. Generally, water dilutions ranging fromabout 1 part by weight up to about parts by weight of water per part bywieght of concentrate can be employed. However, inasmuch as thestability of the diluted concentrates decrease when the weight ratio ofwater to concentrate exceeds 1: 1, about equi-weight ratios arepreferred.

(E) Preferred compositions-The components of the inventive lubricantsare present in the following proportions:

(1) Water-from about 60 to 75 parts by weight.

(2) Thickenerfrom about 2.5 to about 5.5 percent hectorite clay,including optionally from 0.0 to 1.0 part by weight of sodiumcarboxymethylcellulose.

(3) Filler-from about 12 to 29 parts by weight of graphite, includingoptional calcium carbonate.

(4) Surfactantfrom 0.0 to about 0.6 part by weight of a nonylphenolcontaining an average of 9.5 ethoxylate groups in the molecule.

(5) Borax-from about 0.75 to 2.0 parts by weight.

(6) Sodium metasilicate pentahydratefrom 1.5 to 6.5 parts by Weight.

(F) Testing.Three criteria are used to determine the suitability of alubricant sample to perform under operational conditions. They are:

1) Ability to Wet oily metal.A 1:10 ratio of a naphthenic oil in wateremulsion is applied to a small piece of clean boiler plate and allowedto dry. A thin coating of the hot forging compound in diluted aqueousform is applied over the oily metal either by spraying or using a fiberpaint roller. After standing for 5 minutes, the plates are ratedvisually for uniformity of coating. Ratings were either excellent, good,fair or poor.

(2) Brake on test.A clean piece of boiler plate is coated on one sidewith a known amount of hot (forging compound and allowed to dry. Theplate is then placed in a furnace at 1600-1800 F. for 6 minutes. Afterremoval and cooling visual ratings as follows were used: (a) gooduniformresidue, no peeling or cracking; (b) fair--cracking, no peeling; (c)poor--peeling and cracking of residue.

(3) Spray test.-A vertically suspended piece of boiler plate x 10" x A")is heated before three triangularly arranged Fisher burners. The hotforging lubricants are applied by spraying (300 p.s.i.g.) at the nozzle(0.019 inch diameter), and gave a 90 spray pattern from a nozzledistance of 8-10 inches by one sweep requiring 3-4 seconds. The cooledpieces of plate are examined for uniform coverage.

To illustrate the detailed workings of the invention, two preparationsof hot forging lubricants are submitted. Unless otherwise noted, allparts or percentages are by weight and all temperatures are F. ratherthan C.

EXAMPLE 1 Preparation of an illustrative hot forging lubricatingcomposition In this preparation the procedure as disclosed is used togive a composition as given below.

Component: Parts by weight Water 64.1 Hectorite clay 2.9

Nonylphenol ethoxylated with an average of 9.5 ethoxylate groups 0.4Sodium metasilicate- SH O 4.0 Sodium carboxymethylcellulose 0.6 Borax(Na B O -10H O) 1.0 Graphite 27.0

The non-flammable composition is a black, thixotropic semi-solidlubricant, designed to be diluted with Water up to a 1:1 dilution. The1:1 cutback is fluid enough to be pumped and sprayed, shows good hotmetal properties and is non-corrosive to steel and forms a stable,nonsettling product.

EXAMPLE 2 Preparation of a slightly different hot forging lubricantAgain the procedure as disclosed is employed to produce the productwhose composition by weight is disclosed below.

Component: Parts by weight Water 71.5 Hectorite clay 2.9 Sodiummetasilicate-5H O 2.0 Sodium carboxymethyl-cellulose 0.6 Borax (Na2B407'1.0 Graphite 22.0

Preparation of another hot forging lubricant Once more the preparativeprocedure is employed to produce the product whose composition by weightis disclosed below.

Component: Parts by Weight Water 74.6 Hectorite clay 4.0

Nonylphenol ethoxylated with an average of 12 ethoxylate groups 0.4Sodium metasilicate-5H O 3.0 Sodium carboxymethyl-cellulose 1.0 Borax(Na2B407' Graphite 13.0 Calcium carbonate 2.0

When the above lubricant concentrate is cut back 1:1 with water, asatisfactory hot forging lubricant having the desired properties isproduced.

However, when the components of Example 3 are added in a slightlydiiferent sequence, an unsatisfactory lubricant (not sufiiciently stiff)is produced.

For example, using the sample proportions and components above, if theaddition of surfactant to the water is made before the clay is dispersedinto the water system, the grease lacks the necessary stiifness even ifthe remaining components of sodium metasilicate, sodiumcarboxymethylcellulose, borax and calcium carbonate are previouslyprepared and added to the water dispersion of surfactant and clay.

As the preceding specification and examples have indicated, the hotforging lubricants of this invention have several advantages over theknown prior art. For example, in its diluted form (1:1), it providesgood uniform coverage of the hot metal and can be applied by eitherspraying, dipping or by other dispersing methods of the art. It fulfillsits primary function of cooling the workpiece and die, as well assetting the hot metal parts. In addition, the lubricant is non-flammableand minimizes air pollution.

In addition to the above advantages, the novel invention is relativelyflexible in that numerous substitutions, changes and modifications canbe made without departing from the inventive concept.

The true metes and bounds of this invention can best be determined by aperusal of the following claims read in the light of this specification.

What is claimed is:

1. A non-flammable, Water-based, thixotropic hot forging lubricantcomposition concentrate suitable for further dilution with waterconsisting essentially of the following admixture of components in theindicated proportions:

(a) from about 60-75 parts by weight of water,

(b) from about 2.5-5.5 parts by weight of clay thickener selected fromthe group consisting of bentonite and hectorite clays having a particlesize of between 0.05 mm. and 0.01 mm. in diameter and an effectivespecific surface area in the order of 200 to 400 square meters per gramof clay,

(c) from about 12-29 parts by weight graphite,

(d) from about 0.75-2.0 parts by weight borax,

(e) from about 1.5-6.5 parts by weight sodium metasilicate.

2. The lubricant of claim 1 wherein the composition includes up to 0.5part by weight of surfactant selected from the group consisting ofalkoxylated alkyl phenols containing an average of from 2 to 30 moles ofalkylene oxide in the molecule, and where the alkylating group containsfrom 4 to 12 carbon atoms per molecule of phenol.

3. The lubricant of claim 2 wherein the surfactant is an ethoxylatednonylphenol.

4. The lubricant of claim 1 wherein up to 1.0 part by weight of sodiumcarboxymethylcellulose thickener is present in the hot forginglubricating composition.

5. A water-based, non-flammable hot forging lubricant concentrateconsisting essentially of the following components in the indicatedproportions:

6. A hot forging water-based, non-flammable lubricant concentrateconsisting essentially of the following components in the indicatedproportions:

Component: Parts by weight Water 71.5 Hectorite clay 2.9 Graphite 22.0Sodium carboxymethylcellulose 0.6 Sodium metasilicate'5H O 2.0 Borax 1.0

7. A hot forging water-based, non-flammable lubricant concentrateconsisting essentially of the following components in the indicatedproportions:

trate suitable for further dilution with water consisting essentially ofthe steps of admixing (a) from about one-quarter to two-thirds of theweight of water used in the finished water-based lubricant with fromabout 2.5 to 5.5 parts by weight of clay thickener selected from thegroup consisting of bentonite and hectorite clays having a particle sizeof between 0.05 mm. and 0.01 mm. and having an effective specificsurface area in the order of 200 to 400 square meters per gram of clay,and from about 12 to 29 parts by weight of graphite until a homogenousadmixture is formed, and

. (b) admixing a previously prepared homogenous admixture comprisingfrom about 0.0 to 1.0 part by Weight of sodium carboxymethylcellulosefrom about 1.5 to 6.5 parts by weight of sodium metasilicatepentahydrate and from about 0.75 to 2.0 parts by weight of borax withsaid clay-graphite-water mixture until a uniform dispersion is produced,and

(c) admixing said aqueous dispersion with from 00 to 0.5 part by weightof an ethoxylated alkylphenol surfactant and the residual 'water toprepare the desired homogenous, non-flammable, water-based, hot forginglubricant.

9. The process of claim 8 wherein the clay thickener is hectorite, theethoxylated alkylphenol surfactant is a nonylphenol containing anaverage of 9.5 ethoxylate groups per molecule of nonylphenol.

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